chore: simplify provider GetConnection

internal/provider/utils/connection.go

@@ -0,0 +1,60 @@
+package utils
+
+import (
+	"fmt"
+	"math/rand"
+
+	"github.com/qdm12/gluetun/internal/configuration/settings"
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+type ConnectionDefaults struct {
+	OpenVPNTCPPort uint16
+	OpenVPNUDPPort uint16
+	WireguardPort  uint16
+}
+
+func NewConnectionDefaults(openvpnTCPPort, openvpnUDPPort,
+	wireguardPort uint16) ConnectionDefaults {
+	return ConnectionDefaults{
+		OpenVPNTCPPort: openvpnTCPPort,
+		OpenVPNUDPPort: openvpnUDPPort,
+		WireguardPort:  wireguardPort,
+	}
+}
+
+func GetConnection(servers []models.Server,
+	selection settings.ServerSelection,
+	defaults ConnectionDefaults,
+	randSource rand.Source) (
+	connection models.Connection, err error) {
+	servers, err = FilterServers(servers, selection)
+	if err != nil {
+		return connection, fmt.Errorf("cannot filter servers: %w", err)
+	}
+
+	protocol := getProtocol(selection)
+	port := GetPort(selection, defaults.OpenVPNTCPPort,
+		defaults.OpenVPNUDPPort, defaults.WireguardPort)
+
+	connections := make([]models.Connection, 0, len(servers))
+	for _, server := range servers {
+		for _, ip := range server.IPs {
+			if ip.To4() == nil {
+				// do not use IPv6 connections for now
+				continue
+			}
+			connection := models.Connection{
+				Type:     selection.VPN,
+				IP:       ip,
+				Port:     port,
+				Protocol: protocol,
+				Hostname: server.Hostname,
+				PubKey:   server.WgPubKey, // Wireguard
+			}
+			connections = append(connections, connection)
+		}
+	}
+
+	return PickConnection(connections, selection, randSource)
+}